The invention is in the field of high-intensity lamps such as the kind used in motion picture and television productions, as well as in a number of other applications. In recent years there has been a growing interest in the application of medium arc metal halide lamps such as HMI (Hydrargyrum Medium arc length Iodide) type light sources, which are high pressure mercury discharge lamps additionally filled with precise quantities of rare earth metals such as Dysprosium, Holmium and Thallium to yield bright, efficient lighting in the desired visible spectrum. The added materials are included in halide form to create a balanced chemical system to retard bulb wall blackening and degradation of the electrodes.
Typically, these lamps produce a light output which simulates sunlight, operating at approximately 5600.degree. Kelvin (.degree. K) and an efficiency of 100 lumens per watt. The light produced is extremely intense, and bright colors on stage sets and the like are brought out brilliantly by the lamps because of their high intensity and optimal spectral distribution. The arc lengths varies from lamp to lamp, from about 1 cm. to 41/2 cm. depending on overall lamp size.
Although these lamps are built into different types of reflector systems, or in some cases provided without reflectors at all, in all cases the light is discharged onto the scene or work area as a bath of uneven light with hot and cold spots, and color fringing areas, which create an undesired, uneven color temperature and intensity variation throughout the illuminated area.
These lights themselves are marvelous in their intensity, efficiency and spectral distribution. There is a need, however, for a system of diffusing the intense light produced by these lamps so that the uneven illumination with hot and cold spots that the lamps produced is replaced a smooth, even blanket of light which is virtually completely uniform from one spot to the next within the illuminated area.